Effect of PEGylation on Biodistribution and Gene Silencing of siRNA/Lipid Nanoparticle Complexes

ABSTRACT Purpose To determine the influence of physicochemical properties of lipid nanoparticles (LNPs) carrying siRNA on their gene silencing in vivo . Mechanistic understanding of how the architecture of the nanoparticle can alter gene expression has also been studied. Methods The effect of 3-N-[(ω-methoxypoly(ethylene glycol)2000)carbamoyl]-1,2-dimyristyloxy-propylamine (PEG-C-DMA) on hepatic distribution and FVII gene silencing was determined. FVII mRNA in hepatocytes and liver tissues was determined by Q-PCR. Hepatic distribution was quantified by FACS analysis using Cy5 labeled siRNA. Results Gene silencing was highly dependent on the amount of PEG-C-DMA present. FVII gene silencing inversely correlated to the amount of PEG-C-DMA in LNPs. High FVII gene silencing was obtained in vitro and in vivo when the molar ratio of PEG-C-DMA to lipid was 0.5 mol%. Surprisingly, PEGylation didn’t alter the hepatic distribution of the LNPs at 5 h post administration. Instead the amount of PEG present in the LNPs has an effect on red blood cell disruption at low pH. Conclusion Low but sufficient PEG-C-DMA amount in LNPs plays an important role for efficient FVII gene silencing in vivo . PEGylation did not alter the hepatic distribution of LNPs, but altered gene silencing efficacy by potentially reducing endosomal disruption.